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豫西公峪构造蚀变岩型金矿床位于熊耳山东南缘祁雨沟金矿田内,矿体赋存于北东向断裂破碎带内。为探讨成矿流体的来源,尤其是地幔流体参与成矿的程度,选择13件主成矿期的矿石样品进行了系统研究,测定了公峪构造蚀变岩型金矿床成矿系统的温度及其 S、H、O 同位素和惰性气体 He、Ar 同位素组成。对保存于石英中的原生包裹体进行的详细研究结果表明:公峪构造蚀变岩型金矿床中含有丰富的包裹体,其类型复杂多样,有气体包裹体、气液包裹体、液体包裹体、含 CO_2包裹体四种类型。包裹体的均一温度变化范围较宽,在120℃～440℃之间均有分布,可进一步分为150℃～190℃、210℃～250℃和290～350℃三个区间,但主要集中于150℃～250℃的范围内。结合显微镜下观测载金矿物特点,推测金矿的形成温度区间主要在150℃～250℃之间。冰点变化范围较大,在-0.2℃～-9.6℃之间,对应的盐度在0.53wt%～13.51wt%之间。稳定同位素结果表明:硫化物的δ~(34)S 值变化于-1.7‰～2.2‰之间,与陨石硫的δ~(34)S 值接近,反映为深源;成矿Ⅰ阶段流体的δD 值为-68‰～-86‰,δ~(18)O_(H_2O)为+3.5‰～+4.5‰,Ⅱ阶段流体的δD 值为-67‰～-84‰,δ~(18)O_(H_2O)为-3.7‰～+2.6‰,反映成矿流体主要有两个来源,Ⅰ阶段以深源水为主,Ⅱ阶段有大量大气降水混入。氦氩同位素研究表明:公峪构造蚀变岩型金矿床黄铁矿流体包裹体的~3He/~4He 比值为1.05～3.17R/Ra,高于地壳的~3He/~4He 比值100余倍,但明显低于地幔流体的~3He/~4He 比值;~(40)Ar/~(36)Ar=298～391,略高于大气氩的同位素组成;~(40)Ar/~45He 比值0.08～0.35,平均为0.20,与地壳~(40)Ar/~4He 比值一致。He、Ar 同位素组成特征显示了公峪金矿床成矿流体以大气降水为主,但同时有地幔流体成分,推断金矿床成矿作用与地幔活动有着密切的关系。通过与祁雨沟隐爆角砾岩型金矿床的对比研究,认为虽然祁雨沟金矿和公峪金矿赋存于不同的构造环境中,但是流体包裹体及其同位素研究结果显示了二者的成矿作用具有一致性,他们应属于同一成矿系统的产物,均与燕山晚期岩浆热液活动有关,可能为同源、同期、不同构造空间的演化产物。
The structural alteration rock type gold deposit of Gongyu structure in West Henan Province is located in the Qiyuogou gold ore field on the southeastern margin of Xiong’er Mountain, and the orebodies occur in the NE-trending fracture zone. In order to discuss the origin of ore-forming fluids, especially the degree of mantle fluid involved in metallogenesis, 13 ore samples from the main metallogenic stage were selected for systematic study. The temperature of the ore-forming system of the Gongyu structural altered rock gold deposit Its S, H, O isotopes and inert gas He, Ar isotopes. The detailed study on the primary inclusions preserved in quartz shows that the alteration rock type gold deposits in Gongyu tectonics are rich in inclusions of various types, including gas inclusions, gas-liquid inclusions, liquid inclusions , Including CO_2 inclusions four types. The homogenization temperature range of the inclusions is quite wide and distributed between 120 ℃ ~ 440 ℃, which can be further divided into three intervals of 150 ℃ ~ 190 ℃, 210 ℃ ~ 250 ℃ and 290 ~ 350 ℃, but mainly concentrated in 150 ° C to 250 ° C. According to the characteristics of the gold-bearing minerals under the microscope, it is speculated that the formation temperature of the gold ore mainly lies in the range of 150-250 ° C. The range of freezing point is larger, between -0.2 ℃ ~ -9.6 ℃, and the corresponding salinity is between 0.53wt% ~ 13.51wt%. The stable isotope results show that the δ ~ (34) S value of sulfide varies from -1.7 ‰ to 2.2 ‰, which is close to the δ ~ (34) S value of meteorite sulfur and reflects as deep source. δD values ranged from -68 ‰ to -86 ‰ and δ 18 O_ (H_2O) ranged from + 3.5 ‰ to + 4.5 ‰. The δD values of the second-stage fluids ranged from -67 ‰ to -84 ‰ and δ 18 O_ (H_2O) ranged from -3.7 ‰ to +2.6 ‰, reflecting that there are two main sources of ore-forming fluids. Stage I is dominated by deep source water and stage II with a large amount of atmospheric precipitation. The study of helium and argon isotopes shows that the ~ 3He / ~ 4He ratio of pyrite fluid inclusions in Gongyu structural alteration rock type gold deposit is 1.05 ~ 3.17R / Ra, which is 100 times higher than that of crustal ~ 3He / ~ 4He. But slightly lower than the ~ 3He / ~ 4He ratio of the mantle fluid; ~ (40) Ar / ~ (36) Ar = 298 ~ 391, slightly higher than that of the atmospheric argon; ~ 40Ar / ~ 45He ratio of 0.08 ~ 0.35 with an average of 0.20 and consistent with ~ 40 Ar / ~ 4He crust. The characteristics of He and Ar isotopic compositions show that the metallogenetic fluids of Gongyu gold deposit are dominated by atmospheric precipitation, but at the same time have the composition of mantle fluids. It is inferred that the metallogenesis of gold deposits is closely related to the activity of mantle. By comparing with the Qiyuogou cryptoexplosive breccia type gold deposit, it is concluded that although the Qiyuogou gold deposit and Gongyu gold deposit occur in different tectonic settings, the fluid inclusions and their isotopic compositions show that the They are all belong to the same metallogenic system. They are all related to the magmatic hydrothermal activity in the late Yanshanian period and may be the evolutionary products of the same source, contemporaneous and different tectonic spaces.